Teixeira said that the discomfort felt like a spasm, locking up his back below the left shoulder. He was certain that the injury was not to his oblique, an area that often necessitates a stint on the disabled list.
"It's the back. It's not an oblique," Teixeira said. "I've pulled an oblique before, and it's not that. It wasn't on one swing. I woke up this morning, it was tight and it just slowly got worse."
Teixeira went through a full batting practice but was unable to play. Yankees manager Joe Girardi said that he is hopeful that Teixeira will be able to play on Sunday.
"He was a little tight before he went out for BP. When he came in he said he was a little bit tighter," Girardi said. "We decided it was probably best not to play him."
Teixeira was 1-for-4 with a run scored and a sacrifice fly in the Yankees' 7-0 victory over the A's on Friday. He sat out three games in late May with right wrist inflammation, and has batted .235 (8-for-34) with two home runs in 10 games since then.
For the season, Teixeira is batting .241 with a team-leading 11 home runs and 31 RBIs.
Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch and read his MLBlog, Bombers Beat. This story was not subject to the approval of Major League Baseball or its clubs.